fix(constructor): fixed circular references with promoted properties (#272)

Updates the generated mapper code such that circular references are
handled properly when using promoted properties.

Solves #271

Author: Korbeil

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- [GH#272](https://github.com/jolicode/automapper/pull/272) Fixed circular references with promoted properties 
 
 ## [9.4.1] - 2025-06-03
 ### Fixed

src/Generator/MapMethodStatementsGenerator.php

@@ -99,6 +99,29 @@ public function getStatements(GeneratorMetadata $metadata): array
         }
 
         if (\count($duplicatedStatements) > 0 && \count($metadata->getPropertiesInConstructor())) {
+            /**
+             * We know that the last statement is an `if` statement (otherwise we can't add an `else` statement).
+             * Without this logic, the addedDependencies would only be called when the target was set. If the target is
+             * `null` instead, the code looked like:
+             *
+             * ```php
+             * if (null !== result) {
+             *       $result = // Extracted with constructor arguments
+             *       $context = \AutoMapper\MapperContext::withReference($context, $sourceHash, $result);
+             *       $context = \AutoMapper\MapperContext::withIncrementedDepth($context);
+             * } else {
+             *      $context = \AutoMapper\MapperContext::withReference($context, $sourceHash, $result);
+             *      $context = \AutoMapper\MapperContext::withIncrementedDepth($context);
+             *
+             *      $source->propertyName = $this->extractCallbacks['propertyName']($source);
+             * }
+             */
+            $lastStatement = $statements[array_key_last($statements)];
+            \assert($lastStatement instanceof Stmt\If_);
+            $lastStatement->stmts = [
+                ...$lastStatement->stmts,
+                ...$addedDependenciesStatements,
+            ];
             /*
              * Generate else statements when the result is already an object, which means it has already been created,
              * so we need to execute the statements that need to be executed before the constructor since the constructor has already been called

tests/AutoMapperTest.php

@@ -20,6 +20,8 @@
 use AutoMapper\Tests\Fixtures\AddressDTOWithReadonlyPromotedProperty;
 use AutoMapper\Tests\Fixtures\AddressType;
 use AutoMapper\Tests\Fixtures\AddressWithEnum;
+use AutoMapper\Tests\Fixtures\Category;
+use AutoMapper\Tests\Fixtures\CategoryDTO;
 use AutoMapper\Tests\Fixtures\ClassWithMapToContextAttribute;
 use AutoMapper\Tests\Fixtures\ClassWithNullablePropertyInConstructor;
 use AutoMapper\Tests\Fixtures\ClassWithPrivateProperty;
@@ -40,6 +42,7 @@
 use AutoMapper\Tests\Fixtures\Order;
 use AutoMapper\Tests\Fixtures\PetOwner;
 use AutoMapper\Tests\Fixtures\PetOwnerWithConstructorArguments;
+use AutoMapper\Tests\Fixtures\Post;
 use AutoMapper\Tests\Fixtures\SourceForConstructorWithDefaultValues;
 use AutoMapper\Tests\Fixtures\Transformer\MoneyTransformerFactory;
 use AutoMapper\Tests\Fixtures\Uninitialized;
@@ -1376,6 +1379,19 @@ public function testAutoMapperFixtures(string $mapFile, string $directory): void
         }
     }
 
+    public function testCircularReferenceForPromotedProperties(): void
+    {
+        $category = new Category('Category');
+        $category->posts[] = new Post('Example', $category);
+
+        $categoryDTO = $this->autoMapper->map($category, CategoryDTO::class);
+
+        self::assertEquals('Category', $categoryDTO->name);
+        self::assertCount(1, $categoryDTO->posts);
+        self::assertEquals('Example', $categoryDTO->posts[0]->name);
+        self::assertEquals($categoryDTO, $categoryDTO->posts[0]->category);
+    }
+
     public static function provideAutoMapperFixturesTests(): iterable
     {
         $directories = (new Finder())

tests/Fixtures/Category.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\Tests\Fixtures;
+
+class Category
+{
+    /** @var Post[] */
+    public array $posts = [];
+
+    public function __construct(
+        public string $name
+    ) {
+    }
+}

tests/Fixtures/CategoryDTO.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\Tests\Fixtures;
+
+class CategoryDTO
+{
+    /**
+     * @var PostDTO[]
+     */
+    public array $posts = [];
+
+    public function __construct(
+        public string $name,
+    ) {
+    }
+}

tests/Fixtures/Post.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\Tests\Fixtures;
+
+class Post
+{
+    public function __construct(
+        public string $name,
+        public Category $category
+    ) {
+    }
+}

tests/Fixtures/PostDTO.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\Tests\Fixtures;
+
+class PostDTO
+{
+    public function __construct(
+        public string $name,
+        public CategoryDTO $category,
+    ) {
+    }
+}